Timing relay mechanism



E. G. POWELL 2,052,606

TIMING RELAY MECHANISM Filed Feb. 2e, 1934 2 sheets-sheet 1 Dec. l, 1936.

-Wirlwmi- Dec. 1, 1936.

E. G. POWELLy TIMING RELAY MECHANISM Filed Feb. 26, 1934 2 Sheets-Sheet 2 Patented Dec. 1, 1936 UNITED STATES TIMING RELAY MECHANTSM Ellis G. Powell, Michigan-ity, Ind., assignor to j C. A. Dunham Company, Marshalltown, Iowa,

a. corporation of Iowa Application February 26, 1934, Serial No. 713,001

e0 claims.

This invention relates to a new and improved timing relay mechanism, and more particularly to a mechanism for controlling the movement of a motor so that the device actuated A'thereby may be moved slowly from one position to another.

It is frequently desirable to adjust a part slowly from one position to another. For example, in a steam heating system whereV the steam is supplied from a central station, it is desirable to open the-main'steam valve slowly so as to avoid the peak that would bek caused by suddenly throwing the full demand of the entire cold heatf ing system ontol the supply main. By gradually opening this main steam valve, regardless of what the initial Ademands of the heating system may be, this peak is avoided. In other lines of work it is often desirable to bring the equipment up to temperature gradually and to maintain it at this temperature for a given length of time. In such cases a time switch governs the` opening and closing of the valve, and in addition a timing device is desirable to control the rate at Which the valve is opened and closed.

Where the valve, or other mechanism, is operated by'an electric motor itis oftenlimpracticable to provide suficient gear reduction so that the valve may be moved with sufficient slowness this circuit maker and breaker is actuated by 40 an electro-magnetic device the actuating circuits for which are controlled by a pair vof adjustable resistance devices which are balanced whend the motor is at rest. Each of theseresistance devices comprises a movable contact member whereby the effective value of the resistance may be varied, and the movable contact of the control resistance is slowly moved by Ireans of a thermostatically actuated mechanism responsive to the heat developed by an adjustable electric heating element. The movable contact of the other balancing resistance is adjusted more rapidly by the motor so as to successively balance the control resistance as this control resistance 55 is gradually adjusted. and thus cause the motor to be moved slowly, step by step, throughout its range of valve-actuating movement.

'I'he principal object of this inventionis to provide a means for controlling the rate of movement of a value or similar device, as briefly de- 5 scribed hereinabove and disclosed more in detail in the specifications which follow.

Another Objectis to provide an electrically operated. timing device which may be operated at low potential so that the device may be located 10 remote to the valve-operating device which it controls and which may be run at a. minimum of expense.

Another object is to provide such a timing device which is adjustable. so that the rate of move- 15 ment of the actuated element may be varied within the maximum timing interval. I

Another object is to provide a device of this kind which is simple, inexpensive in construction, and reliable in operation. 20

Other objects and advantages of this invention will be more apparent from the following detail description of one approved form of mechanism constructed and operating according to the principles of this invention.

In the accompanying drawings:

Fig. i is a diagrammatic view illustrating the principal elements of the timing mechanisms and the wiring connections therefor.

Fig. 2 is a diagrammatic elevation showing a 30 typical heating system with this timing control mechanism applied thereto. i

Reference will iirst be made to Fig. 2 which shows a typical steam heating system which is supplied with steam through the branch main D leading from a central station or other suitable Ksource of steam supply.A

This supply main D may be provided near its inlet end with a steam-separator l, a normally open cut-off or gate valve 2, and an automatic 40 reducing valve 4 which may be either manually orL thermostatically adjusted to reduce the pressure and temperature of the steam before it is delivered to the radiating system. The reduced pressure steam is delivered through risers 5 into the radiators 6 provided at their outlets with. steam traps l through which condensate -and non-condensable gases are drawn out into the return pipe 8 which leads to a suitable exhausting mechanism indicated generally at E which serves to withdraw and vent the noncondensable gases, collect the condensate and deliver it tova suitable receptacle, and maintain a lower pressure in the return pipe 8 than in the radiators 6 so as to assure the evacuation of the radiators. The actuating motor 9 for the exhausting apparatus E is controlled by a diierential-pressure controller I and a floatcontrolled switch II. The power for operating this electrical apparatus is delivered through the mains I2 and I3 provided with the main cutout switch I4. The heating system thus briefly described by Way of example is of the sub-atmospheric differential-pressure type disclosed in several prior art patents, for example the patent to Clayton A. Dunham No. 1,644,114, granted October 4, 1927. As far as the present invention is concerned, any approved type of heating system could be supplied with steam from the supply main D. At 3 is indicated a motor-operated cutoff valve positioned in the supply main D; the present invention being particularly concerned with the automatic control and operation of this valve: 3.

It will now be apparent that if this heating system is cold and the main valve 3 is quickly and completely opened, there will be a sudden rush of steam into the heating system which steam will be quickly condensed so as to cause a protracted demand on the steam supply, this demand greatly exceeding the normal demand, that is'the amount of steam required to keep the radiating system filled after the system is once heated up and in normal operation. 1n order to avoid this excessive demand or peak load, means is provided for opening the valve 3 very slowly so as to cut down the initial supply of steam to the heating system and not permit a free flow of steam through themain until the system has been heated up to approximately the normal operating temperature.

The valve 3 is opened and closed by a motor mechanism indicated generally at A, this motor being controlled by a system of relay devices in the panel board B, which relay mech- -anisrn is in turn controlled jointly by the timing-switch mechanism C and the motor A. The opening or closing of valve 3 is initiated through the timing mechanism C by means of a suitable circuit making and breaking device such as the manually operable switch I5, a thermostat I6, or a time-operated switch I1. Any one or all of these devices may control the timing mechanism C, it only being necessary that some device be used to close a circuit when it is desired that the valve 3 be opened and to break this circuit when the valve is to be closed.

The construction and operation of the devices A, B and C will now be better understood by referring to the diagrammatic showing in Fig. 1. The motor assembly A comprises the motor A', preferably a small single phase alternating current motor, which is equipped with two sets of windings, one for clockwise and the other for counter-clockwise rotation. This motor is adapted, through suitable reduction gearing, to open or close the valve 3 (Fig. 1) or to operate any other suitable device. Within the motor case a reduction gearing connects the rotor o! the motor to a shaft I8 upon which is mounted the crank arm I9 having the pin and slot connection 20 with one arma! a lever 2| intermediately pivotedat 22. TheI other `arm of this lever carries the movable contact 23 o! the balancing resistance device indicated generally at X. This device comprises a suitable arcuate resistance member connected between the two terminals 24 and 25 and adapted to be divided into twc elective portions by the movable contact device 23. Wires 26, 21 and 28 lead motor A. Wire 38 leads from binding post 35v to the spring arm 39 which carries the central movable contact 4|) of a motor-control switch F.

Y, This switch mechanism also comprises a pair of adjustably mounted fixed contacts 4I and 42 between which the contact 40 is positioned so as to be out of engagement with both xed contacts when in neutral position. Movement of contact 40 to the left will engage iixed contact 4I, and movement to the right will engage ilxed contact 42. The contacts 4| and 42 are connected respectively by wires 43 and 44 with the terminals 45 and `46 on the panel board, which in turn are connected by wires 41 and 48 with the terminals 50 and 5I of motor A'. One winding of motor A (for example, the winding which will cause clockwise rotation) is connected between the terminals 58 and 31, whereas the other winding (for example, for causing counter clockwise rotation) is connected between the terminals I and 31. Therefore it will be seen that when the movable contact'4 40 of control switch F is moved into engagement with ilxed contact 4I the motor A will rotate in one direction, i'or example clockwise, and that when movable contact 48 is moved into engagement with xed contact 42 the motor will rotate in the opposite direction. When movable contact 48 oi' switch F is in the central or neutral position the motor A' will be at rest.

The primary coil 52 of transformer G is energized through wires 53 and 54 connected respectively to power terminals 34 and 35. The secondary 55 of transformer G` furnishes low-voltage current suitable for operating the relay mechanism through wires 56 and 51 to the central terminals 58 and 59 respectively. Binding post 58 is connected through wire 68 and protective resistance 6I with terminal 3|, and' binding post 59 is similarly connected through wire 62 and protective resistance 63 with the terminal 29. Binding posts 58 and 59 are respectively connected by wires 64 and 65 with the two terminals of coil 66 of a balanced solenoid H. A centrally tapped terminal 61 of the solenoid coil 65 is connected through wire 68 with the panel terminal 38. 'I'he core 69 of solenoid H. is connected through stem 18 and spring connection 1I with the iiexible spring arm 12 whichcarries the central contact member 13 of the switch mechanism J. 'I'he contact 13 is positioned between and is adapted to engage alternatively with the adjustably xed contacts 14 and 15 of this switch J. The fixed contact 14 is connected 'through wire 16 with a terminal 11 tapped onto a few end turns of the solenoid coil 6 6. In a similar manner switch lterminal 15 isV connected through wire 18 with a terminal 19 tapped onto a few turns at the opposite-end of solenoid coil 66. The end terminals of coil 88 of a second balanced solenoid 4K are connected by wires 8I and 82 with the power binding posts 58 and 59 respectively. A terminal 83- tapped into the central portion of coil 88 is connected through wire484 and protective resistance 84' to the flexible support 12 for movable contact 13 of switch J. The core 85 of balanced solenoid K is connected through stem 86 with the 75 in parallel between the wires |05 and 505 of the' free end of spring support 39 for the movable A`contact 40 of motor-switch F. When a current of uniform strength is flowing throughall parts of solenoid coil 80, the core 85 will be held in the central position shown in Fig. l, thus moving contact 40 to itscentral neutral position out of en- The timing mechanism C comprises' a control resistance Y which is similar to the balancing resistance X already described, these resistances being equal and equally distributed between the end terminals thereof. The end terminals ill and 88 of resistance Y are connected by wires S9 and 90 to the terminal binding posts @l and 92 re.- spectively, these binding posts being connected through wires 93 and 9G to the terminals il and 29 on the panel board B. The movable contact member t of control resistance Y'is (in thek example here shown) mounted at the free end of a thermostatic bar 96 xed at its other end Sil. When bar 9&5 is cold or at normal room temperature, it will extend in the position shown in solid lines so as to hold movable contact 95 at one end of the control resistance, that is substantially at the terminal El. When this thermostatic bar @Si i's sufficiently heated, it will warp into the position shown in dotted lines so as to move the contact 95 to the other end of the resistance, that is substantially into engagement with terminal dt. Movable contact 95 is connected through bar d@ and wire @t with binding post 9@ which is connected through wire IIlIl with. the terminal dit on panel board B.

The thermostatic bar 9S is surrounded by or closely associated with a suitable electric heating element here shown as consisting of the iour heating elements lill, |02, |03 and I0@ connected heating circuit. Wires ID'I and I08 extend from the power mains I2 and I3 to the binding posts M19 and Il@ on the timing unit C. Binding post 09 is connectedcthrough wire I I I to one terminal of the primary coil II2 of a transformer L, the

other terminal vof the transformer being connected through wire II3 to.a third binding post II@ of the timing device C. Wires IE5 and liti connect the binding/posts I III and i It to the ter- Q minals of the control switch M, which may correspond to any one or all of the circuit making and breaking devices I5, I6 and I1 shown in Fig. 2 and hereinabove described. The heating circuit exrheostat N, the intensity of the heatingy current can be varied thus changing the time interval required for heating the thermostatic bar 96 so that it will warp from one of its positions to the other. By adjusting the movablecontact I-I8jin a clockwise direction to itsv extreme position so as to cut out all of the resistance of the rheostat, the

maximum heating current will be obtained and the bar 96 will be heated more rapidly so as to move contact 95 from one end of resistance if to the other in a minimum time. When rheostat contact i i8 is adjusted in the opposite or counter clockwise direction so as to insert all of the resistance in vthe heating circuit, the heating current will be diminished so as to heat the bar 96 more slowly and a maximum time will be required to move the contact 95 from one end of resistance Y to the other. For example, in one commercial form of the device the time interval of operation of this resistance mechanism (which as will be hereinafter apparent corresponds to the time interval required for opening the valve) may be varied from a minimum of approximately eightor ten minutes to a maximum of approximately thirty-five minutes. It will be understood that these figures are given merely by way oi example, and that the time intervals can be changed by properly designing and proportioning the several elements or" the mechanism.

As far as the operation of the timing device C is concerned, it will now be apparent that as long as the control switch Mis open no current will iiow through the heating circuit, the thermostatic bary 9d will remain in the position shown in solid lines, and all of the resistance Y will be included in the circuit between binding posts @2 and 99, the binding post 9i being shorted directly to the binding post @9 through wire 89, .contact $5, thermostatic bar 9G, and wire S8. When control switch M is closed, the transformer L will be energized to furnish reduced voltage current to the heating circuit, the intensity of this heating current being determined by the setting of rheostat N. The thermostatic b ar 96 will then be gradually heated so as to slowly move the contact 95 along the length of resistance Y, y

thus inserting a gradually increasingportion of this resistance between the terminals 9i and 99, and gradually decreasing the portion of the resistance in circuit between terminals 99' and 92.. When switch M is again opened, the heating circuit will be broken and the parts will gradually cool off so as to return the movable contact 95 to the solid line position shown in the drawings.

IThe complete operation of the cooperating mechanisms A, B and C can now be described substantially as follows: it will be noted that the reduced voltage current from transformer G,`

which is delivered to the central terminals 58 and titl, ows through both balanced solenoids H and K2 the end terminals of each of these solenoids being bridged across the power terminals 5S and 59. When the' mechanisms are in the first inactive position shown in Fig. l, panel terminal 29 will Ibe snorted to panel terminal 3|! through wire 26, resistance terminal 24, movable contact 2t, and wire 26. In a similar manner panel terminal Sil is shorted to panel terminal 3l through wire Mld, wire 98, thermostatic bar 96, movable contact 95, and wires 89 and 93. The lefthandihalf of coil 66 of solenoid H is bridged across through the following shunt circuit: From the end terminal of th coil through wires Slt and 60, protective resistance 6I, the short circuit previously described between panel terminals 3I and 3U, and wire Beto the central tapped terminal 6l! of the coil. In an exactly similar manner the right-hand half of -the coil is shunted through the following circuit: From the other end terminal oi the coil through wires and 62, protective resistance 63, the previously described short circuit between panel terminals 29 and 30, and wire 68 to the central terminal 6'I.4 Since the two protective resistances 6I and 63 are equal, the resistances of these two shunt circuits will be the' same and the same current will flow through all portions of the solenoid coil 66 so that the core 69 will be held in the central neutral position now shown in Fig. 1. Consequently switch J will bein a central and neutral position and no current will ilow through the wire 89 extending to the movable contact of this switch from the central terminal 83 of solenoid K. Therefore the same current will flow through all portions of coil 80 of solenoid K and the core 85 of this solenoid will be held in the central vor neutral position and switch F will be open so that neitherl winding of motor A' will be energized and the motor will be at rest.

If now the control switch M is closed so as to cause the heating element of timing relay 'C to be energized, the thermostatic bar 96 'will gradually become heated and will warp so as to begin to move the' contact 95 along the control resistance Y. The resistances between panel terminals 29 and 30, and 30 and 3| will now no longer be balanced. The terminals 29 and 30 will now be bridged by two shunt circuits, one oi' which is shorted through resistance device X as already described, and the other of which includes somewhat less than the entire resistance Y. Panel terminals 39 and 3| are bridged by two shunt circuits one of which includes all of the resistance X, and the other of which includes a` small portion of resistance Y. It will therefore be seen that the total effective resistance between terminals 29 and 30 will be less than the resistance between terminals 30 and 3|. As a result a higher resistance will be bridged across the left-hand half of coil 66 of solenoid H than the resistance bridged across the right-hand half of the coil. Therefore a larger current will ilow through the left-hand half of the coil and the core 69 will be drawn toward the left bringing the movable contact 13 of switch J into engagement with xed contact 14. This will complete a shunt circuit from central terminal 83 of solenoid K through wire 84, protective resistance 84", contacts 13 and 14 of switch J, wire 16, a few end turns of solenoid coil 66, and wires 64 and 8| to the right-hand end terminal of solenoid coil 80. One result of this will be to increase the current owing through the left-hand end of solenoid H so as to more firmly hold the switch J in the position to which it has just been moved. A second result is to greatly decrease the current flowing through the right-hand half of solenoid coil 89 since this half of the coil is now short-circuited through the shunt circuit last described. As a consequence the core of this solenoid K will be drawn toward theleft bringing the contacts 48 and 4| of switch F into engagement thus completing an energizing circuit between .terminals 31 and 50 of motor A so as to cause'rotation of the motor. in a clockwise direction. This rotation of the motor will start the adjustment of the valve or other device driven by the motor and at the same time will,

through crank and lever connections I9, 20 and halves of solenoid H will again be equalized and y switch J will be returned to its central position so as to break the circuit shunted about onehalf of solenoid K which will also be returned to central position so as to open the switch F and stop the motor A'. However, the thermostatic bar 96 will continue to warp so as to move the contact farther away from the end terminal 81 of control resistance Y thus again unbalancing the resistances between panel terminals 29, 30 and 30, 3| so that solenoids H and K and switches F and J will again be moved as before to again complete the motor circuit and cause further rotation of the motor A in a clockwise direction. This will adjust balancing resistance X so as to again balance the resistances and restore the parts to neutral position thus again stopping the motor. 'I'his cycle of events will be successively repeated at intervals until the thermostatic member 96 has reached its extreme position as shown in `dotted lines in Fig. 1 at which time the motor will have completed the adjustment of the valve 3 or other means driven by the motor.

When the valve or other device is to be returned to its original position, the switch M will be opened so as to break the heating circuit in relay mechanism C. The thermostatic bar 96 will now cool oi and gradually return to its original position. As this movement takes place the resistances will be successively unbalanced and balanced as before but in the opposite direction, that is the resistance between panel terminals 29, 30 will at intervals become greater than the resistance between panel terminals 30, 3|, as a result of which greater currents will tlow in the right-hand halves of solenoids H and K causing the switches J and F to be moved toward the right and causing the motor A' to be energized so as to rotate in a counter clockwise direction. Except for this general reversal in the direction of the several movements, the cycle of operations will be the same as previously described and the valve will be gradually closed, or the equivalent device driven by motor Ay will be returned to its original position.

While the rheostat N has been here disclosed as incorporated in the timing mechanism C, it will be apparent that this rheostat, like the switch M, might be located at any accessible location and connected with the timing mechanism by extensions of the wires |96 and ||9. 'I'his may be desirable in case the timing mechanism is to be located in some relatively inaccessible position, so as to facilitate adjustment of this mechanism for varying the time interval in which the valve is opened.

It will also be apparent that by adding any suitable means for adjusting the proximity o1' the thermostat 96 to the heaters |0|, |92, |03 and |04 it is possible to further vary the time interval required for the opening and closing of the valve.

I claim:

1. 'Iiming mechanism for controlling the operf ation of an electrically actuated device, said mechanism comprising a circuit including a resistance and a contact movable along the resistance to progressively vary the amount oi' the re- `sistance eiective in the circuit, a thermostatic member for moving the contact, an electric heating element for the thermostatic member, and means for controlling the flow of current through the heating element.

2. Timing mechanism for controlling the operation of an electrically actuated device, said mech'- 75 aocacoc anism comprising a circuit including a resistance and a contact movable along the resistance to progressively vary the amount of the resistance eiective in the circuit, a thermostatic member for moving the contact, an electric heating element for the thermostatic member, a circuit for energizing the heating element, and an adjustable rheostat in this circuit.

8. 'Iiming mechanism for controlling the operation of an electrically actuated device, said mechanism comprising a circuit including a resistance and a-contact movable along the resistance to progressively7 vary the amount of the resistance eiiective in the circuit, a thermostatic member for moving the contact, an electric heating element for the thermostatic member, a circuit for energizing the heating element, an adjustable rheostat in this circuit, and an automatically actuated control switch for the heating circuit.

d. Timing mechanism for controlling the operation of an electrically actuated device, said mechanism comprising a circuit including a resistance and a contact movable along the resistance tc progressively vary the amount oi the resistance eiective in the circuit, a thermostatic bar on which the contact is mounted, an electric heating element for causing the bar to warp to move the contact, and means for controlling the flow of current through the heating element.

5.' Timing mechanism for controlling the operation of an electrically actuated device, said mechanism comprising a circuit including a resistance and a contact movable along the resistance to progressively vary the amount of the resistance effective in the circuit, a thermostatic bar on which the contact is mounted, anielectric heating element for causing the bar to warp to move the contact, a circuit for energizing the heating element, and an adjustable rheostat in the heating circuit.

6. Mechanism for controlling the time interval of movement of a device comprising a motor for moving the device, an energizing circuit for the motor, a switch in this circuit, electromagnetic. means for opening and closing the' switch, and circuits for controlling the electromagnetic means comprising a balancing resistance, means operated by the motor for adjusting this resistance, a control resistance comprising a movable contact member for adjusting the eiective value of the resistance, a thermostatic memberfor moving the contact member, an electric heating element for the thermostatic member, a heating circuit for the heating element, and means for controlling the flow of current in this circuit.

7. Mechanism for controlling the time interval of movement of a Idevice comprising a motor for moving the device, an energizing circuit for the motor, aswitch in this circuit, electromagnetic means for opening and closing the switch, and circuits for controlling the electromagnetic means comprising a balancing resistance, means operated by the motor for adjusting this resistance, a control resistance comprising a movable contact member for adjusting the effective value of the resistance, a thermostatic member for moving the contact member, an electric heating element for the thermostatic member, a heating circuit for the heating element, and an adjustable rheostat in this circuit.

. 8. Mechanism for controlling the time interval of movement of a device comprising a reversible motor for moving the device in either direction, a pair of energizing circuits for the motor, one

adapted to cause rotation of the motor in one direction and the other in the opposite direction, a switch member movable in opposite directions from a neutral position to alternatively close either circuit, an electromagnetic means for moving the switchl, member, and circuits controlling saidv electromagnetic means comprising a control resistance anda balancing resistance each including a movable contact member for adjusting the eiiective value of the respective resistance, means for slowly movingthe contact of the control resistance, means actuated by the motor for more rapidly moving the contact of the balancing resistance in the same effective direction so as to cause a step by step movement of the motor in a direction determined by the direction of movement of the controlresistance contact, the means for moving the control resistance Contact comprising a thermostatc member, an electric heat'- ing element, a heating circuit for this element, and an adjustable rheostat in the heating circuit.

9. in combination with a heating system comprising a steam supply main, a valve for controlling the ow of steam through the main to the heating system, mechanism for automatically opening and closing the valve, means for automatically imparting predetermined step by step movements to said mechanism with substantial time intervals between said movements so as to slowly move the valve fron completely closed to completely open position, and means for selectively timing the length of the intervals between the step by Step movements of said mechanism so as to materially change the length of time required for a complete valve movement.

l0. 'in combination with a heating system comprising a steam supply main, a valve for controlling' the flow of steam through the main to the heating system, an electricmotor for opening or closing the nvalve, mechanism for automatically imparting predetermined step by step movements to said motor with substantial time intervals between said movements so as to slowly move the valve from completely closed to completely open position, and. means for selectively timing the length of the intervals between the step by step movements of the motor so as to materially change the length of time required for a complete valve movement.

ll. in combination with a heating system comprising a steam supply main, a valve for controlling the flow ci steam through the main to the heating system, an electric motor for opening or closing the valve, mechanism for controlling the motor comprising a motor energizing circuit, a switch in this circuit, electromagnetically actuated means ior opening and closing the switch, and actuating circuits for the electromagnetic means comprising a control resistance and a balancing resistance in each actuating circuit, means actuated by the -motor for adjusting the balancing resistances to intermittently balance the resistances of the actuating circuits, and means for' slowly and continuously varying the control resistances.

l2. lin combination-with a heating system comprising a steam supply main, a valve for controlling the now of steam through the main to ing or closing the valve, mechanism for controlling the motor comprising a motor energizing ciri' the heating system, an electric motor for openi means comprising a control resistance and a. Y

balancing resistance, means actuated by the motor for adjusting the balancing resistance, means for slowly varying ,the control resistance comprising a movable contact member, a thermostatically operated member for moving the contact, an electric heating element for the thermostatic member, and means for controlling the ow of current through the heating element.

13. In combination with a heating system comprising a steam supply main, a valve for controlling the flow of steam through the main to the heating system, an electric motor for opening or closing the valve, mechanism for controlling the motor comprising a motor energizing circuit, a switch in this circuit, electromagnetically actuated means for opening and closing the switch, actuating circuits for the electromagnetic means comprising a control resistance and a balancing resistance, means actuated by the motor for adjusting the balancing resistance,

means for slowly varying the control resistance comprising a movable contact member, a thermostatically operated member for moving the contact, an electric heating element for the thermostatic member, a circuit for energizing the heating element. and an adjustable rheostat in this circuit. 1

14. Mechanism for controlling the time interval of movement of a device comprising a reversible motor for moving the device in eitherdirection, a pair of energizing circuits for the motor one adapted to cause rotation oi the motor in o ne direction and the other in the opposite direction, a switch member movable from a neutral position'to alternatively close either circuit, an electro-magnetic means for moving the switch member, a pair of actuating circuits for the electromagnetic means, a control resistance and a balancing resistance included in these actuating circuits, a pair of movable contact members one movable lengthwise of each resistance to divide the resistance into two effective portions, one portion in each actuating circuit, means for slowly and continuously moving the contact of l'the control resistance lfrom one end of the resistance to the other to progressively unbalance the circuits, and means actuated by the motor to more rapidly but intermittently move the contact of the balancing resistance to intermittently l balance the circuits, thus causing a step by step movement of the motor in a direction determined by the direction of continuous movement oi the control resistance contact.

15. Mechanism for controlling the time interval oi movement of a device comprising a reversible motor for moving the device in eitherr direction, a pair of energizing circuits for the motor one adapted to cause rotation of the motor in one direction and the other in the opposite direction, a switch member movable from a neutral position to alternatively close either circuit, an electro-magnetic means for moving the switch member, a pair of actuating circuits for the electro-magnetic means, a control resistance and a balancing resistance included in these actuating circuits, a pair of movable contactmembers, one movable lengthwise of each resistance to divide the resistance into two effective por` tions, one portion in each actuating circuit, thermostatically operated means for slowly and continuously moving thecontact ofthe control resistance Iromone end of the resistance to the other to progressively unbalance the circuits, and

means actuated by the motor to more rapidly but intermittently move the contact of the balancing resistance to intermittently balance the circuits, thus causing a step by step movement of the motor in a direction determined by the direction of continuous movement of the control resistance contact.

16. Mechanism for controlling the time interval of movement of a device comprising a reversible motor for moving the device in either direction, a pair of energizing circuits for the motor one adapted to cause rotation of the motor Vin one direction and the other in the opposite direction, a switch member movable from a neutral position to alternatively close either circuit, an electro-magnetic means for moving the switch member, a pair of actuating circuits'for the electro-magnetic means, a control resistance and a balancing resistance included in these actuating circuits, a pair of movable contact members one movable lengthwise oi each resistance to divide the resistance into two eiective portions, one portion in each actuating circuit, means for slowly and continuously moving the contact of the control resistance from one end of the resistance to the other to progressively unbalance the circuits, and means actuated by the motor to more rapidly but'intermittently move the contact of the balancing resistance to intermittently balance the circuits, thus causing a step by step movement of the motor in a direction determined by the direction of continuous movement of the control resistance contact, the means for moving the control resistance contact comprising a thermostatic member on which the contact is mounted, an electric heating element for the A thermostatic member, a heating circuit for the heating element, and means for regulating the ilow of current in this heating circuit.

17. Mechanism for controlling the time interf tral position to alternatively close either cir- @i5 cuit, an electro-magnetic means for moving the switch member, a pair of actuating circuits for the electro-magnetic means, each actuating circuit including a control resistance and a balancing resistance, automatically operating means for slowly and continuously increasing one control'resistance and decreasing the other to unbalance the circuits and cause the switch to be closed and energize the motor, and means actuated by the motor at a more rapid rate to intermittently change the relative values of the balancing resistances to intermittently balance the circuits and open the switch, thus causing a step by step movement of the device.

18. Mechanism for controlling the time interval of movement of a device comprising a reversible motor -for moving the device in either direction, a pair o'f energizing circuits for the motor one adapted to cause rotation of the motor in one direction and the other in the opposite direction, a switch member movable from a neutral position to alternativelyclose either circuit, an elecbalance the circuits and cause the switch to be 76 :losed and energize the motor, and means actuated by the motor at a more rapid rate to intermittently change the relative values of the balancing resistances to intermittently bal-ance the circuits and open the switch, thus causing a step the length of the intervals between the step by step movements of said mechanism.

20. In combination with a heating system com prising a steam supply main, a valve for control,-r ling the flow of steam through the main to the heating system, an electric motor for opening orw closing -the valve, mechanism for automatically causing a predetermined step by step movement of the motor to gradually move the valve from completely closed to completely open position, and means comprising an electrically heated thermostat for selectively timing the length of the intervals between the step by step movements of the motor.l

ELLIS G. POWELL. 

